Electronic coordinating system



Nov. 28, 1950 Filed June 8I 1945 I5v Sheets-Sheet 1 gwuwvfo'm T Robert Burmqhc John F. Clark Jv:

Gum/ww Nov. 2s, 195o Filed June 8,v 1945 T. R. BURNI'GHT ETAL ELECTRONIC COORDINATING SYSTEM 3 Sheets-Sheet 2 T Roberl Burnlqh John F.' Clark Jr.

NOV- 28, 1950 T. R. BURNIGHT l-:rAL 2,531,393

- ELECTRONIC COORDINATING SYSTEM Filed June 8, 1945 3 Sheets-Sheet 3 www,

Patented Nov. 28.,

2,531,393 ELECTRONIC COORDINATING SYSTEM T. Robert Burnight, Washington, D. C. and John F. Clark, Jr., United States Navy Application June 8, 1945, Serial No. 598,350

(Granted under the act of March s, lass, as

192s; 37o o. o.. 757) 9 Claims.

amended April 30,

This invention relates to coordination of oper- I ation of radio echo ranging systems and impulse transmitters automatically responsive to a remotely transmitted signal.

Radio echo Yranging systems recurrently transmit'irnpulses and receive echoes thereof from remote obstacles. The transmitted impulses have a duration of the order of a few microseconds, and normally recur at a frequency lying in the low audio range. 'Ihe echo-receiver is normally insensitive, but is rendered operative for a short interval following each operation-of the transmitter. For instance, to receive echoes from a range up to 40 nautical miles, the receiver must be operative for a period of- `495 microseconds after a transmitted impulse.

For navigational and identification purposes other impulse transmitters are employed which are automatically responsive to a remotely transmitted signal which is usually of an impulse character. A remote aircraft may activate such a beacon transmitter recurrently for a limited period of time by transmitting the requisite signal.

The operation of the beacon transmitter is manifestly not under control at the local installation. AUnder many circumstances ranging systems and beacons must be installed in close proximity, and the broad frequency spectrum of the impulse type signals employed by the beacons results in disabling interference with the ranging systems. 'I'he operation of the ranging systems, however, normally requires only isolated intervals aggregating a minor fraction of the elapsed time of their employment.

It is accordingly an object, of this invention tovpermit operation oi' remotely activated impulse transmitters during inoperative periods of an echo-ranging installation.

' It is a further object of the invention to eiect coordinated simultaneous employment of echoranging land remotely activated signalling systems."

v The invention will be described with reference to the appended exemplary drawings, of which:

Figure 1 is a block diagram of an installation comprising four echo ranging systems, coordinating apparatus, and a plurality of remotely activated signalling systems;

Figure 2 is a schematic diagram of an embodiment =of the coordinating apparatus shown in block form in Figure 1;

:Figure 3 is a showing, partly schematic and partly in block form, of one means by which control voltage for keying the coordinating apparatus may be obtained from an echo-ranging system;

Figure 4 is a drawing, partly schematic and partly in block form, showing one means by which output voltage from the coordinating apparatus can be employed to control a remotely-activated signalling system.

Referring to Figure l, echo-ranging system I is coupled to coordinating apparatus I6 in any manner operative to cause a control voltage to appear at input I1 of coordinating apparatus I6 when ranging system I transmits a pulse of en'- ergy. The magnitude and duration of'thisvbltage may lie anywhere within wide'lirnits.v In a specific construction, the control voltage could be an impulse of any amplitude between and 300 volts and any duration between 0.5 and 50 microseconds.

Echo ranging systems 2, 3 and 4 supply corr-A trol voltage respectively to inputs. I8-, I9 and 20. Ranging systems I and 2 are adjusted to show echoes from substantially the same maximum range; ranging systems 3 and 4 likewise are set for the same maximum range, which'may be different from that for which systems 'I and 2 are operative.

The control impulses at terminals I'I and I8 are combined in mixer circuit 5. The voltage impulses appearing at the output of mixer circuit 5 are passed through limiting and sharpening circuit 1. The impulses at the output of-circuit v 'l areof uniform amplitude and very shrtduration. Each impulse at the output of circuit 1 coincides in time with the leading edge of an impulse applied at terminals I1 or I8. Mixer 6 and limiting and sharpening circuit 8 function in the same manner as circuits 5 and 'I except that circuits 6 and 8 are actuated by control impulses applied to input terminals I9 and 20 by ranging systems 3 and 4.

The short-duration impulses at the output of circuit 1 are employed to trigger the rectangular voltage generator 9. The duration of the rectangular voltage impulses 'produced by circuit 9 may be varied within wide limits and should be ad.'-` justed to be slightly greater than the sensitive period characteristic oi the receivers in ranging systems I and 2. The impulses at the output oi' circuit 8 are similarly employed to trigger rectangular voltage generator I0. The duration of the rectangular impulses at the output of circuit I0 is variable, and it should be set to a value slightly greater than the sensitive interval characteristic of the receivers in ranging'systems 3 and assises The rectangular voltage waves at the output of circuits 9 and lil are combined, limited and ampliiled in circuit II. The output of circuit II is connected to the'input of cathode follower I2 and to the input of power ampliiler I3. The output of cathode follower I2 goes to output channel 5Il: that of power ampliiiei I3 goes to output channel 52. The potential at output channels 50 and 52,is zero relative to ground so long as no ranging receiver is sensitive to signals. When any oi' the ranging systems sends out an impulse.

a substantial positive voltage appears at output1 channel' 50, remaining for the duration of the rectangular impulse produced at the output of circuit Ii. Simultaneously, a negative voltage appears at output channel 52, continuing for the duration of the unstable state, and thus the duration oi the output rectangular voltage impulses from the multivibrators, may be varied within wide limits with variable resistors 31 and 38 for the upper and lower channels respectively.

The rectangular voltage waves produced by the vtwo -imultivibrators are appliedby direct `*coupling respectively to the grids of tubes 33 and 4l which are part of the circuit represented in Figure 1 by block II. The rectangular waves from the two i multivibratorsare combined and limited by tubes remotely-activated signalling systems inoperative. Dual output channels aiording control voltages of either polarity are provided because both receivers are insensitive to signals. Then the potentials at the output terminals return to zero and the impulse transmitters resume normal operation until the next time a ranging system sends out an impulse.

The stages in "the coordinating apparatus are conductively coupled from the rectangular voltage generators through to the output channels, so that there is no time limit on the duration oi' the output control voltages. e

Figure 2 shows a detailed schematic diagram ci an exemplary embodiment of the coordinating apparatus shown in block form in Figure 1. In this embodiment positive control impulses from the echo-ranging systems may be fed in at jacks I1, I8, I5 and 20. Tubes 25, 26 21 and 28 are the input mixer tubes represented in Figure 1 by blocks 5 and 6. The limiter and impulse sharpener elements, shown in Figure 1 as blocks 1 and f I, comprise tubes 29 and 3|, in the upper channel, and tubes 30 and 32, in the lower channel. The mixer tubes are coupled to tubes'29 and 30 respectively by resistance-capacitance circuits 2|, 22 and 23, 24, which have very short time constants. Other short time-constant coupling circuits 54, 55 and 56, 51 are used to couple tube 29 to tube 3i and tube 3l! to tube 32 respectively. As a result of the operation of these circuits, together with the large negative bias on tubes 3i and 32, the trigger impulses appearing at the cathodes of tubes 3i and 32 are of about one-hall.| microsecond duration.

The rectangular voltage generator circuits, shown in Figure 1 as blocks 9 and III, comprise tubes 33. and tubes 34, 36 respectively, connected as cathode-coupled multlvibrators having a stable state and an unstable state. Either of the multivibrators may be thrown into its unstable state by a positive impulse applied to the grid of its normally non-conducting tube, which in the upper channel is tube 33 and in the lower channel is tube 34. Trigger impulses for this purpose are applied to the grid of tube 33 by tube 3i and to the grid o f tube 34 by tube 32. The

35 and 40, with theirl associated circuit. The plates oi' tubes 39 and 40 are connected together and conductively coupled through voltage divider 0I, 62 to the control grid of tube 42, which with its associated circuit comprises the remainder of block I'I in Figure 1. Immediate dynamic circuit responseis eirected by small capacitance 4I connected from the plates oi tubes 33 and 40 to the control grid oi' tube 42.v

The output of tube 42 is conductively coupled to tube 46 through voltage divider 63, 64 and to tube 45 through voltage divider 65, 56. Immediate dynamic response in these coupling circuits is achieved by small condensers 43 and 44.

Tube 45 is the cathode follower shown in Figure 1 as block I2. Its grid is normally biased below plate current cutoff, so that its cathode, which is connected to output jacks 50 and 5I, is normally at ground potential. When a rectangular voltage impulse from either multivibrator is impressed on the circuit, the grid of tube 45 is made more positive, plate current flows in tube 45, and

a positive voltage appears at output jacks 50 and 5I, remaining so long as either multivibrator is producing a rectangular impulse.

Tube 46 is the power amplifier shown inFigure 1 as block i3. Its grid is normally biased below plate current cutoff, and its plate, which is con' tems in any convenient manner.4 The impulses may vary within wide limits as to amplitude and duration, the major requirement being that the pulses must occur simultaneously with the transmission of radio energy impulses by the ranging system. Most echo-ranging installations have suitable impulses available at one or more points in the timing circuit.

Simple apparatus for obtaining positive control impulses from an echo-ranging system is shown in Figure 3. Block 10 represents the transmitter of a ranging system; coil 1I represents a portion of the resonant circuit in which the system produces radio frequency currents during its intervals of transmission. Coil 1I is shown inductively coupled to the antenna of the ranging system which is represented by block 13. Also loosely coupled to coil 1I through coupling link 12 is the tank circuit composed of coil 14 and condenser 15 in parallel, which is resonant at the radio frequency produced by the ranging system. One side of tank circuit 14. 15 is grounded; the other side is connected to the plate of diode 18. The cathode of diode 'I8 is returned to ground through resistor 1I and condenser 15in parallel.

Thetime constant of capacitance-resistance circuit 15, Ii is long relative to a radio frequency period' but short relative tothe duration ofthe `transmitted impulse of radiov\energy. When .an impulse is transmitted by the ranging system, an impulse ,positive with respect, to groundiwill appear at the cathode of diode 18.' Thisvimpulse may be used'as a control voltage at the input of the coordinating apparatus herein described.

In Figure 4 a simple method'is shown for using the positive control voltage produced atthe out'- put of the control apparatus to desensitize a remotely-activated signalling system. The block Illll in Figure tirepresents the signalling system including the impulse transmitter |09 and its associated receiver-keyer apparatus |05. In nornal operation the receiver-keyer receives radio signals from remote points and responsively thereto keys the transmitter, causing it to send out impulses of radio energy. Tube IDI, the tube to be controlled by the coordinating apparatus, is shown in schematic form as a part of receiverkeyer |05. It may be any tube in the signal channel of the receiver-keyer. If the receiver employs a super-regenerative detector tube, it may be convenient to apply the control voltage to that tube. The cathode of tube IDI is connected to ground through resistor |02. The positive output of the coordinating apparatus is applied to tube `lill between cathode and ground. When no voltage is present at the output of the coordinating apparatus, tube IUI is free to operate normally. When, in response to an impulse from a ranging system, the voltage at the output of the coordinating apparatus assumes a positive value, the cathode of tube IUI is raised to a positive potential such that the tube is blocked and renderedwholly inoperative. Hence neither the receiver-keyer nor the impulse transmitter can function so long as the positive voltage from the coordinating apparatus persists.

The voltage from the negative output channel of the coordinating apparatus will perform a similar function when connected in the gridreturn circuit of the tube to be controlled in the receiver-keyer.

It will be understood that the embodiments shown and described are exemplary only, and that the scope of the invention will be determined with reference to the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Whatis claimed is: t

l. In combination, an impulse echo ranging system; a remotely-actuated impulse transmitting system; and control means for the transmitting system operative to desensitize the same in response-to the reception of pulses from said ranging system.

period including the maximum return period ofl desired echoes fromsaid ranging system. Y.

`4. In combination, arecurrently operative radio echo ranging system; a remotely activated-.impulse transmitting` system; vand control means for the transmittingsysteml operative to desensitize the same responsively to operation of the ranging system' for a period including the maximum return period of desired echoes, Aand before the next ranging operation.

5. In combination, nrst and second radio echo ranging systems; a remotely activatedimpulse signalling system; rst control means for the signailing system operative responsively to the operation of the first ranging system to desensitize the signalling system for a predetermined time interval including the maximum return period of desired first system radio echoes; and second control means for the signalling system operative l to the signalling system operative to desensitize.

` the signalling system during the duration of the control voltage.

'7. In combination, a plurality of recurrently operative radio echo ranging systems; a remotely activated impulse system; a voltage generator; control means coupled to the ranging systems operative responsively to each ranging operation to cause the voltage generator to initiate a control voltage continuing for the maximum return period of desired radio echoes; and circuit means coupling the voltage generator to the signalling system operative to desensitize the signalling system during the duration of the conger impulses from a control element andv operative responsively to each trigger impulse to produce lll) a signal voltage of predetermined duration; signal combining means conductively coupled to all of said relay means operative to produce an output voltage during operation of any of said relay means; and means conductively coupled to the signal combining means operative to desensitize the signalling systemresponsively to the output voltage from the signal combining means.

9. The recurrently operative radio echo ranging systems; a remotely activated impulse signalling system; multivibrator Ameans having a stable state and an unstable state of predetermined time duration which may be initiated by a control voltage; means coupling the ranging systems to the multivibrator means operativeto apply thereto a control voltage coincident with operation of either 7 ranging system; and means eoupung' the mum- UNITED STATES PATENTS vibrator to the signalling system operative to de- Number Name Date Sensiue the Signal-ung System whne the 2,189,549 Hershberger Feb. o. vibrator means is in the unstable state. 405.238 Seeley M 6. 1943 T. ROBERT BURNIGHT. 5 2,421,017 Deloraine May 27, 1947 JOHN F. CLARK, Jn. 2,460,202 Tyson Jan. 25, 1949 2,467,564 Okrent Apr. 19, 1949 REFERENCES CITED The following references are of record in the lo FQREIGN PATENTS 111e of this patent: I Number Country Date 497,147 Great Britain Dec. 9, 1938 

